title: Mechanical damage to Gram-negative bacteria by surface plating with the Drigalski-spatula technique.
abstract: Colony counting by spreading bacterial suspensions on plating media by various techniques is of general concern. Comparative studies between hand plating (Drigalski-spatula technique) for different time intervals and spiral plating resulted in significant differences in colony counts. Lower counts of Gram-negative bacteria were obtained by using hand plating for more than 10s, compared with short time hand plating (5s) or spiral plating. Colony counting of Gram-positive bacteria showed no differences between both techniques. Further characterisation of Escherichia coli cells spread with the Drigalski-spatula technique by electron microscopy revealed a large number of damaged cells compared to control samples. The data clearly shows that the mechanical forces during hand plating are sufficient to damage E. coli cells.
authors.affiliation: heipha Dr. Müller GmbH, Eppelheim, Germany. reiner.hedderich@heipha.de
authors.forename: Reiner
authors.initials: R
authors.lastname: Hedderich
authors.forename: Rolf
authors.initials: R
authors.lastname: Müller
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Greulich
authors.forename: Norbert
authors.initials: N
authors.lastname: Bannert
authors.forename: Gudrun
authors.initials: G
authors.lastname: Holland
authors.forename: Petra
authors.initials: P
authors.lastname: Kaiser
authors.forename: Rolf
authors.initials: R
authors.lastname: Reissbrodt
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D015169:Colony Count, Microbial; D006090:Gram-Negative Bacteria / Q000254:growth & development / Q000648:ultrastructure*; D008854:Microscopy, Electron